This research evaluates the level of service of one of the main roads in Lima (Peru), which is 'Vía Expresa Paseo de la República'. Specifically, the section of this road between Canada and Javier Prado Avenues was evaluated. For this, the first step was to film the vehicular flow at both ends of the section studied, in order to obtain the number of vehicles that transited every certain period of time, which allows to measure the Traffic Flow (between 1,200 to 2,100 veh/h/lane). Then, the time taken by the vehicles to move a certain distance defined in the films was estimated, which allowed estimating, with a harmonic average, the Space Mean Speed (between 20 and 65 km/h). After that, using the Greenshields equation and the fundamental traffic equation, a regression algorithm in R language is used to identify the theoretical quadratic relationship between both measured variables and thus obtain the characteristics of the road, which are the Free-Flow Speed (between 70 to 90 km/h) and the Jam Density (between 85 to 110 veh/km). In this way, with the measured parameters, the HCM 2000 standard is used to know the level of service of the evaluated road, obtaining as a result an F level.